Chart contour question
 

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

--

Roger Long

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

===================

Depends on the chart.

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

Roger,

I just took a quick look at one of mine (13283), and it looks like the
contour lines correspond to the sounding numbers, which - as I'm sure
you know - are mean low low water, not mean low water.

The soundings are in feet, and the contours are multiples of six feet
(i.e. fathoms) that seem to line up with them.

Regards,
Al
s/v Persephone

Follow the contour line on the chart you are using. At some point along
that line there will be a break, with the depth (say, 5 fathom curve) that
the particular contour line denotes.

otn

"Roger Long" wrote in message
...
Would someone please refresh my memory about the sounding contour lines on
charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is that
right?

--

Roger Long

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?


Depends on the chart. The chart title block should show the units for
soundings (most Canadian chart now give depths in metres). You should
be able to determine the contour intervals by looking at the
surrounding soundings. Canadian charts often have numbers indicating
the contour depth inserted in the contour line.

There is an excellent publication called "Chart 1: Symbols and
Abbreviations" that should be available from any chart dealer. It
will tell you more than you ever wanted to know about the symbols and
abbreviations used on nautical charts. (note that both Canadian and
US authorities produce a "Chart 1", but the content is different!!)


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

It also depends on what country produced the chart.

Some use Lower Astronomical Tide which is becoming the standard.

Canada uses Lower Normal Tide.

US charts use Mean Lower Low Water.

Most countries are using metric depths on charts.

Jack

__________________________________________________
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
__________________________________________________

On Sun, 06 Mar 2005 20:44:33 -0500, Wayne.B
wrote:

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

===================

Depends on the chart.


I cast around, and found sources that seemed to indicate fathom
isobaths, fathom n feet for shallow isobaths, others marked in
meters, or feet.

I guess, user beware....

Brian Whatcott Altus OK

"Roger Long" wrote in message
...
Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

--
Up here (Atlantic Canada) most of the charts are in fathoms...but some in
feet and some in meters. I always check the 'legend' to be sure.

On Mon, 07 Mar 2005 04:46:45 GMT, Brian Whatcott
wrote:

On Sun, 06 Mar 2005 20:44:33 -0500, Wayne.B
wrote:

On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:

Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?

===================

Depends on the chart.


I cast around, and found sources that seemed to indicate fathom
isobaths, fathom n feet for shallow isobaths, others marked in
meters, or feet.

I guess, user beware....

For any chart, you should read the legend block. It has indispensable
info, including the units of the soundings and the chart datum.

And, Chart #1 is also necesary for understanding the conventions in
use.



Rodney Myrvaagnes NYC J36 Gjo/a


"Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia

I found the new paperback by Calder surprisingly good. I picked it up
thinking it was for beginners and would spent the first half
explaining which way is North, but its a clear, concise, modern
treatment of the topic. And it includes Chart #1.

How to Read a Nautical Chart : A Complete Guide to the Symbols,
Abbreviations, and Data Displayed on Nautical Charts
by Nigel Calder



Peter Bennett wrote:
On Mon, 07 Mar 2005 00:23:03 GMT, "Roger Long"
wrote:


Would someone please refresh my memory about the sounding contour
lines on charts?

They are fathom lines, the first 6 feet MLW, the next 12, etc. Is
that right?



Depends on the chart. The chart title block should show the units for
soundings (most Canadian chart now give depths in metres). You should
be able to determine the contour intervals by looking at the
surrounding soundings. Canadian charts often have numbers indicating
the contour depth inserted in the contour line.

There is an excellent publication called "Chart 1: Symbols and
Abbreviations" that should be available from any chart dealer. It
will tell you more than you ever wanted to know about the symbols and
abbreviations used on nautical charts. (note that both Canadian and
US authorities produce a "Chart 1", but the content is different!!)